Below are the drawings for the pomona box modifications

After acquiring some new equipment for the labs, a few of us spent time on Thursday and Friday sorting through everything and storing them into their appropriate places. New vacuum parts, power supplies, cables, and much more were included. The rooms are now ready for the lab tours commencing Tuesday afternoon.

Below is attached the ADC noise floor of two CyMAC channels vs the Red Pitaya.

The frequency resolution of these RIN spectra are 16 Hz, with N_meas = 19,308,426 for the CyMAC, and N_meas = 263,024.

[Christina, Ma, Tyler]

Pomona Box completed and is now on the server rack in 1119. Additionally, the photodetectors were connected to the box and set up in front of the heater elements.

I've been looking into the performances of individual channels on the Cymac by computing their individual PSDs and corresponding CSDs that show their noise relation to each other. It appears some channels do have lower noise floors than others, and some combinations of these actually do perform similar to the Red Pitaya (showing below the CSD between CHs 3 and 5), although it doesn't look like it's much of an improvement. The best method as of now still appears to be phase-locking two separate ADCs to reduce the correlated noise floor further.

This can be further discussed at the July 22, 2025 group meeting.

[Christina, Ma, Tyler]

Yesterday, Ma and I started taking data for the PSD/CSD measurements while the photodetectors and one of the heater elements are on (8) and are using the Red Pitaya to compare it to the data we took for the same measurements on the CyMAC. It will be finished Wednesday morning, and then we plan on starting to take additional recordings in order to conduct the same type of comparison for the dark noise measurements.

[Ma, Christina, Tyler]

Figure 1 shows the following PSDs for channels 0-15 from the 14 hour test. Figure 2 shows the reduced chi squared and CSD plots for both the 2 Hz and 16 Hz resolutions.

[Ma, Christina, Tyler]

ADC CyMAC 260 hr, 8192Hz sampling rate channels V3 and Vref6

[Tyler, Ma, Christina, Maple, Cece, Mary, Pooyan, Audrey]

We started by cleaning outside of the cleanroom wiping down the cable channel and working our way down while taking the pre-cleaning measurement. We then stated wiping down the inside of clean room and vacuumed, mopped the outside of the cleanroom. Finally, we vacuumed, mopped, and wiped down the floor inside the cleanroom.

Particle Count Measurements:

• Pre-cleaning (2:00 pm):
  • Zone 3:
    • 0.3 µm: 2707
    • 0.5 µm: 1374
    • 1.0 µm: 249
  • Zone 4:
    • 0.3 µm: 2207
    • 0.5 µm: 1166
    • 1.0 µm: 374

• Post-cleaning (4:30 pm):
  • Zone 3:
    • 0.3 µm: 4082
    • 0.5 µm: 2415
    • 1.0 µm: 708
  • Zone 4:
    • 0.3 µm: 1707
    • 0.5 µm: 791
    • 1.0 µm: 416

Simulating how point absorber defects on Advanced LIGO mirrors affect cavity performance by modeling a 4km LIGO-like arm cavity with a point absorber fixed at 5cm off-center on the ITM. In this simulation, displaced the laser beam across a 21×21 grid while calculating the deformation, then measuring the resulting power loss in the cavity (~283W circulating power).

Date and Time: Around 4:20 PM on Auguest 6, 2025

Location and Temperature:

• Back of the room 1119, around the working station: 90.2 °F
• Front of the room 1119, around the doorway: 85.8 °F
• Back of the room 1129, around the working station: 93.4 °F
• Front of the room 1119, around the doorway: 82.3 °F
• In the hallway in front of room 1119: 77.2 °F

[Ma, Tyler, Christina]

This past week, we were able to set up the data streaming for continuous acquisition to the PCs, and can conduct the initial tests now. We were able to do this by:

• Installing the correct OS ecosystems to each Red Pitaya
• Installing the terminal streaming client
• Debugging formatting and file saving issues by saving the data in a TDMS file on the host PC.

Updated CyMAC measurement, comparing 260 hrs of measurement time vs. 405 hrs.

These are the frequency averaged and veto binned plots for the initial Red Pitaya and CyMAC systems.

Below are slides giving an update on RH O6 design progress.

Below are slides discussing RIN infrastructural updates related to the CyMAC.

Slides

We have tested the heater to find emissivity, mounted the heater system to the optical table, and have taken irradiance maps of the heater projected onto the screen.

The heater's emissivity was determined by using a thermocouple in conjunction with the FLIR's temperature calibration. To attach the thermocouple to the heater initially, I used Kapton tape and ran both the wires of the heater and the thermocouple through the heater bridge. This allowed for the heater to rest on an optical post and be observed without anyone directly holding it, but there were some measurement issues. The thermocouple had a very wide range of temperatures it was reading, which may have been due to intermittent contact or a short between the two legs of the thermocouple. To solve this and make the temperature measurements more stable, we pried apart the two ends of the thermocouple (to ensure there was no short) and put tape on either side, leaving the end connection bare. This was then taped to the heater, and the thermocouple was much more stable. We also used a K-type thermocouple that has an adhesive tape on it already, which assisted with the intermittent contact as well. With the thermocouple measuring the temperature of the heater, we could point the FLIR directly at the heater and calibrate the emissivity until the FLIR and the thermocouple agreed. Cassidy's emissivity calculator was also used, as I could input a temperature and observe what the emissivity of an area was based on that temperature. We found the emissivity of the heater to be 0.57.

As a note, when observing the heater with the FLIR, it appeared that there was a hot spot in the center, where the Kapton tape sat. Because the Kapton has a different emissivity than the 304 stainless steel of the heater, the FLIR will read it as having a different temperature than it actually does. When using the FLIR in the future, be sure to ascertain whether there is a temperature difference somewhere or if there may be different emissivities.

Additionally, the first heater that I used was taken to a very high temperature and oxidized. The emissivity of this oxidized heater is not known, but could be good information for knowing how oxidation affects these heaters specifically.

To mount the heater system in front of the screen, I used 1/2'' optical posts and the mount I designed using COMSOL's CAD program. The heater was originally 2.5 inches away from the screen, and has since been moved back by an additional two inches so that we could observe the heater side of the screen with the FLIR. We wanted to see what temperature the heater side of the screen was when irradiated by the heater, and how that compared to the camera side of the screen. When the heater ran at 1.12 W of input power, the heater side of the screen had a max temperature of around 29.7 C, and the camera side of the screen read at about 29.5 C. This means that there is very little thermal loss between the two sides of the screen, and any insulation that the screen's adhesive may have is largely negligible. Additionally, the camera was placed at an angle and undetermined distance for these tests, confirming that the temperature measurements compensate well/don’t depend on changes in angle or distance between the camera and the screen. However, there was spots on the back of the screen that the camera was measuring as hot spots where there shouldn’t have been any. I have included an example below. It would be useful to run a test where the camera is directly on the back of the screen without the heater to characterize the screen and see if the hot spots are physically present on the screen or if this is an artifice of the camera because of something like angle of viewing.

Taking irradiance maps of the screen was straightforward. After checking that the emissivity of the screen is 0.99 by viewing it at room temperature, we monitored the max temperature while slowing increasing the wattage the heater was running at. There is not a large change until the heater is at around 95 C, at which point the screen began to rise in temperature from 27 C to 28 C. We took measurements of this while the heater was 2.5 and 4.5 inches away from the screen. The irradiance map has a very symmetrical and circular shape, but does not have the ring pattern that we expected. There may be a few reasons for this: there could be some conduction between the two sides of the screen that is causing the pattern to spread further, the heater setup may not be as ideal as it was modeled to be, or there could be a different, unknown issue.

TO DO:

- It would be useful to run a test of the camera in multiple different positions to ensure our conclusion that the camera’s measurements don’t depend on angle or distance (or that these factors are well accounted for in the current temperature calculations) is correct.

- Measure the back of the screen straight on to identify bright spots and possible reasons as to their appearance.

- Recalibrate camera to ensure it is still correct after testing in multiple positions.

- Take another irradiance map of the screen at a higher input power, as well as moving the heater close/further away to try and replicate the COMSOL irradiance maps. It would be useful to also redo the COMSOL modeling at lower powers and variable distances.

Pictures included of full table setup, the heater mount, the heater with Kapton tape attaching the thermocouple as well as FLIR's measured irradiance map.